In flight, a pilot navigates their aircraft according to a flight plan that is filed with the air traffic control authorities. The flight plan may be manually or electronically loaded into the aircraft's Flight Management System (“FMS”) at the beginning of the flight, prior to departure. Among other things, the flight plan typically includes a plurality of geographic waypoints that define a planned track of the aircraft and the specific times at which the aircraft is to arrive at those waypoints. The flight plan may also require that assent maneuvers, descent maneuvers and turn maneuvers be conducted at some of those waypoints. The flight plan, when associated with aircraft performance information from aircraft sensors such as fuel burn rates, crew costs and atmospheric information, determines important flight performance measurements such as, for example, fuel consumption, environmental impact, estimated times of arrival (“ETA”), and flight overhead costs.
It is a common occurrence for an air traffic control authority to request a change in an aircraft's flight plan during flight. Such requests may be made for a variety of reasons, such as to re-schedule landings at a particular airport or to maintain aircraft separation. An air traffic control authority request is also known as a “clearance.” Clearances are commonly communicated to an aircraft in flight and may be displayed in the aircraft's Cockpit Display Unit (“CDU”). Exemplary, non-limiting types of a CDU include a Data-link Cockpit Display Unit (“DCDU”) and a Multi-Purpose Cockpit Display Unit. (“MCDU”). Typically, the flight crew reviews the clearance and evaluates the change in the flight plan to determine the impact of the clearance on the aircraft's fuel supply, its ETA and other flight parameters such as its speed of advance, crew costs and overhead costs. The pilot then either signals the acceptance of the clearance with a positive or a “Wilco” response, or signals the rejection of the clearance with an “Unable” response. These responses are usually accomplished by manipulating a physical transducer, such as a button or a switch, that is located proximate to an electronically rendered selection label.
In order to make a decision whether to accept or reject a clearance, a pilot typically runs the original flight plan through the FMS to obtain a set of flight parameters based on the original flight plan. The pilot may then key in changes to the flight plan in compliance with the clearance. The pilot may process the amended flight plan back through the FMS to obtain a pro forma set of flight parameters. The pilot then manually compares both sets of flight parameters to determine the acceptability of any resulting changes in ETA, changes in fuel consumption, environmental impact, flight overhead costs, etc. Such a procedure may result in significant heads down time, during which the pilot's attention may be diverted. Therefore, there is a need to improve the clearance decision process to minimize administrative work load and eliminate heads down time.